During the VD process, the metallurgical work takes place in the steel ladle. The liquid steel ladle is placed in a vacuum tank, which is connected to a vacuum pump system. The ladle is equipped with porous plugs through which inert gas is injected into the melt in order to promote stirring. Depending on the metallurgical reactions during the process ladle freeboards of 800 - 1200 mm are required. If equipped with an additional oxygen lance further benefits such as forced decarburization or chemical heating can be obtained, as known under VD-OB.